The present invention relates to a force sensor suitable for incorporation into a shoe for detecting application of a persons foot to a supporting surface and to apparatus suitable for receiving and processing signals received from such sensors. In particular the present invention relates to the use of such equipment for sports training and athlete monitoring applications.
A known in-shoe dynamic pressure measuring system is produced by Novel GmbH and marketed as the xe2x80x98pedarxe2x80x99 range. With reference to the Novel internet web site (http://www.novel.de/pedar.htmxe2x80x94viewed 31st Oct. 2001), the system is presented as one which includes in-shoe sensors in the form of in-soles with tails extending from each insole for establishing a wired connection with monitoring equipment. The intended applications of the system include gait analysis, rehabilitation assessment, shoe research and design, field testing of sport applications and long term load monitoring. An emphasis is placed on the ability to perform accurate and reliable pressure distribution measurement for monitoring of local loading of the foot inside the shoe. A computer aided calibration procedure allows all sensors of the pedar system to be calibrated individually by using a process employing homogeneous air pressure.
The pedar system is available as a package including analysis software and a number of insoles each having a plurality of sensors distributed over the insole area. The system would appear to be directed to the medical and research market and as such is of an arrangement and cost which make it less suited to mass market commercialisation in the field of sports training and athlete monitoring applications.
It is an object of the present invention to provide a sensor which may be located in a shoe and which is suitable for use in the field of sports training and athlete monitoring applications.
In accordance with a first aspect of the present invention there is provided a sensor for detecting the presence of a force exerted by a persons foot on a supporting surface, said sensor arranged to be interposed between the foot and the supporting surface and therefore subjected to the force, in response to which force the sensor exhibits a change in an electrical characteristic, said sensor comprising:
a resilient compressible material exhibiting a first surface and a second surface and at least partially accommodating one or more electrically conductive body shaped and orientated within the material such that when the compressible material is in an uncompressed state the separation of the first and, second surfaces is sufficient that the conductive body or bodies do not extend to span the first and second surface simultaneously, whereas when the sensor is subject to the force the compressible material adopts a compressed state having reduced separation between the first and second surfaces such that the conductive body or bodies extend to and span the first and second surfaces simultaneously; and
contact portions adjacent each of the first and second surface for making electrical connection with the electrically conductive body or bodies when they extend to the or each first and second surface.
Therefore, in one arrangement the act of compressing the resilient compressible material, therefore reducing the separation between its first and second surface may allow one or more of the electrically conductive bodies to reach the first and second surface simultaneously. If this occurs, the or each electrically conductive body will provide a path of relatively low electrical resistance between the resilient compressible material first and second surface (in comparison with the condition when the electrically conductive bodies do not extend to span the first and second surface) and therefore between the first and second contact portions adjacent the first and second surface. Thus, the act of applying a force to compress the resilient compressible material brings about a change of electrical characteristic when measured at the contact portions, in particular a reduction in electrical resistance, to provide an electrical switching action. Removal of the compressive force allows the resilient material to return to its uncompressed state. In some cases the application of force bringing about compression may cause one or more electrically conductive body to protrude beyond the first or second surface.
One or more of the conductive bodies may consist of more than one part each arranged to unite and collectively extend to the first and second surface simultaneously when the material adopts a compressed state. Thus, in regions of the compressible material in the non-compressed state one or more such parts may be arranged in separated fashion leading from one said surface towards the other said surface. Indeed, it is possible for such a body to exhibit parts which extend to the first and second surface simultaneously but which are not united either directly or via intermediate parts when the compressible material is in an uncompressed state, but are united when the compressible material is in a compressed state.
One or more of the conductive bodies may comprise an electrically conductive element disposed and orientated within the compressible material to extend substantially in a direction from the first surface to the second surface, such that when the compressible material is in an uncompressed state the separation of the first and second surfaces is sufficient that the conductive element does not extend to the first and second surface simultaneously, whereas when the sensor is subject to the force the compressible material adopts a compressed state having reduced separation between the first and second surfaces such that the conductive element extends to the first and second surfaces simultaneously. In this case the conductive bodies compress by a lesser extent than the compressible material in their immediate vicinity, or substantially not compress at all.
The conductive body or bodies may be of metal or metal coated materials. The conductive bodies may be of conductive polymer materials.
Optionally, at least one of the contact portions is deposited on the first or second surface of the resiliently compressible material.
At least one of the contact portions may be of electrically conductive paint, electrically conductive ink or an electrically conductive polymer.
At least one of the contact portions may comprise conductive textile material.
The sensor may be divided into a plurality of sensor areas and capable of detecting the presence of the force in a said sensor area.
The sensor may be connectable to processing apparatus for receiving and processing signals from said sensor. In this case, the sensor may be connectable to processing apparatus by wireless communication means.
In accordance with another aspect of the present invention there is provided a shoe insole comprising the sensor.
In accordance with another aspect of the present invention there is provided a shoe comprising the insole.
In accordance with another aspect of the present invention there is provided a shoe comprising the insole, the insole being removable.
In accordance with another aspect of the present invention there is provided a shoe comprising the sensor.
In accordance with another aspect of the present invention there is provided a processing apparatus connectable to the sensor, said apparatus configured for receiving and processing signals from said sensor, the apparatus comprising:
input means to receive signals from said sensor;
means for processing the signals in accordance with processing instructions; and
output means for providing output data based on the processed signals.
The output data may include a representation of the force exerted by a persons foot on a supporting surface based on signals received from a said sensor interposed between the foot and the supporting surface. The output data may include an indication of distance travelled by a user exerting a force with their foot on a supporting surface, based on signals received from a said sensor interposed between the foot and the supporting surface. The output may be in the form of a visual, audible or tactile representation. The output may include data derived from the distance travelled.
In accordance with another aspect of the present invention there is provided a system comprising the technical features of the processing apparatus and the sensor.
In accordance with another aspect of the present invention there is provided a system comprising the technical features of the processing apparatus and the shoe insole.
In accordance with another aspect of the present invention there is provided a system comprising the technical features of the processing apparatus and the shoe.
These and other aspects of the present invention appear in the appended claims which are incorporated herein by reference and to which the reader is now referred.